Kubernetes Networking Deep Dive: CNI, eBPF, NetworkPolicy, and Service Mesh

<p>Go beneath Kubernetes Services and Ingress to the layer that actually moves packets: the CNI contract that gives every Pod an IP, the difference between overlay and underlay networking, and how NetworkPolicy locks down Pod-to-Pod traffic — but only if your CNI actually enforces it. You'll follow a real three-microservice Flask/PostgreSQL app through a default-deny NetworkPolicy, a migration to the eBPF-based Cilium CNI with Hubble observability, and finally a service mesh (Istio) adding automatic mTLS, traffic splitting, retries, and circuit breaking. Along the way you'll build the judgment to know when a service mesh is worth its operational cost — and when it isn't yet.</p>

Tools: kubernetes, cni, cilium, ebpf, istio, mtls